/*
 * FreeRTOS V202212.00
 * Copyright (C) 2020 Amazon.com, Inc. or its affiliates. All Rights Reserved.
 *
 * Permission is hereby granted, free of charge, to any person obtaining a copy of
 * this software and associated documentation files (the "Software"), to deal in
 * the Software without restriction, including without limitation the rights to
 * use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of
 * the Software, and to permit persons to whom the Software is furnished to do so,
 * subject to the following conditions:
 *
 * The above copyright notice and this permission notice shall be included in all
 * copies or substantial portions of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS
 * FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR
 * COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER
 * IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
 * CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
 *
 * https://www.FreeRTOS.org
 * https://github.com/FreeRTOS
 *
 */

#include "cbmc.h"

/*
 * We allocate a TCB and set some members to basic values
 */
TaskHandle_t xUnconstrainedTCB( void )
{
    TCB_t * pxTCB = pvPortMalloc( sizeof( TCB_t ) );

    if( pxTCB == NULL )
    {
        return NULL;
    }

    __CPROVER_assume( pxTCB->uxPriority < configMAX_PRIORITIES );

    vListInitialiseItem( &( pxTCB->xStateListItem ) );
    vListInitialiseItem( &( pxTCB->xEventListItem ) );

    listSET_LIST_ITEM_OWNER( &( pxTCB->xStateListItem ), pxTCB );
    listSET_LIST_ITEM_OWNER( &( pxTCB->xEventListItem ), pxTCB );

    if( nondet_bool() )
    {
        listSET_LIST_ITEM_VALUE( &( pxTCB->xStateListItem ), pxTCB->uxPriority );
    }
    else
    {
        listSET_LIST_ITEM_VALUE( &( pxTCB->xStateListItem ), portMAX_DELAY );
    }

    if( nondet_bool() )
    {
        listSET_LIST_ITEM_VALUE( &( pxTCB->xEventListItem ), ( TickType_t ) configMAX_PRIORITIES - ( TickType_t ) pxTCB->uxPriority );
    }
    else
    {
        listSET_LIST_ITEM_VALUE( &( pxTCB->xEventListItem ), portMAX_DELAY );
    }

    return pxTCB;
}

/*
 * We set the values of relevant global variables to
 * nondeterministic values, except for `uxSchedulerSuspended`
 * which is set to 0 (to pass through the assertion)
 */

void vSetGlobalVariables( void )
{
    uxSchedulerSuspended = pdFALSE;
    xTickCount = nondet_ticktype();
    xNextTaskUnblockTime = nondet_ticktype();
}

/*
 * We initialise and fill the task lists so coverage is optimal.
 * This initialization is not guaranteed to be minimal, but it
 * is quite efficient and it serves the same purpose
 */
BaseType_t xPrepareTaskLists( void )
{
    TCB_t * pxTCB = NULL;

    __CPROVER_assert_zero_allocation();

    prvInitialiseTaskLists();

    /* The current task will be moved to the delayed list */
    pxCurrentTCB = xUnconstrainedTCB();

    if( pxCurrentTCB == NULL )
    {
        return pdFAIL;
    }

    vListInsert( &pxReadyTasksLists[ pxCurrentTCB->uxPriority ], &( pxCurrentTCB->xStateListItem ) );

    /*
     * Nondeterministic insertion of a task in the ready tasks list
     * guarantees coverage in line 5104 (tasks.c)
     */
    if( nondet_bool() )
    {
        pxTCB = xUnconstrainedTCB();

        if( pxTCB == NULL )
        {
            return pdFAIL;
        }

        vListInsert( &pxReadyTasksLists[ pxTCB->uxPriority ], &( pxTCB->xStateListItem ) );

        /* Use of this macro ensures coverage on line 185 (list.c) */
        listGET_OWNER_OF_NEXT_ENTRY( pxTCB, &pxReadyTasksLists[ pxTCB->uxPriority ] );
    }

    return pdPASS;
}

/*
 * We stub out `xTaskResumeAll` including the assertion and change on
 * variables `uxSchedulerSuspended`. We assume that `xPendingReadyList`
 * is empty to avoid the first loop, and xPendedTicks to avoid the second
 * one. Finally, we return a nondeterministic value (overapproximation)
 */
BaseType_t xTaskResumeAllStub( void )
{
    BaseType_t xAlreadyYielded;

    configASSERT( uxSchedulerSuspended );

    taskENTER_CRITICAL();
    {
        --uxSchedulerSuspended;
        __CPROVER_assert( listLIST_IS_EMPTY( &xPendingReadyList ), "Pending ready tasks list not empty." );
        __CPROVER_assert( xPendedTicks == 0, "xPendedTicks is not equal to zero." );
    }
    taskEXIT_CRITICAL();

    return xAlreadyYielded;
}
